This invention relates to a dental tool, and more particularly to a nozzle for a dental tool for delivering two fluid streams to teeth of a patient.
Air-water syringes are used by dentists and dental technicians for cleaning debris from a patient's teeth and mouth. The teeth and mouth are cleaned by the spraying of a water stream, or an air stream, or a mixed air-water stream from the syringe. A typical air-water syringe has a hand-piece and a nozzle releasably attached to the hand-piece The nozzle has a first passageway through which air away flow and a second passageway through which water away flow. When the nozzle is attached to the hand-piece, the first passageway communicates with an air conduit in the hand-piece and the second passageway communicates with a water conduit. The nozzle is retained in the hand-piece by a retaining collar, attached to a threaded stem in the hand-piece, which compresses an 0-ring into a groove on the outer surface of the nozzle to form an interference fit for resisting withdrawal of the nozzle from the hand-piece. Between uses of the syringe, the nozzle must be removed from the hand-piece and sterilized or be replaced with a sterile nozzle.
Disadvantages encountered with such a syringe are the difficulty in readily removing the nozzle from the hand-piece, cleaning the nozzle and sterilizing it. An air-water syringe described in U.S. Pat. No. 4,975,054 (incorporated herein by reference) overcomes these disadvantages by use of a disposable nozzle having first and second fluid passages with coaxial intake ports and coaxial discharge ports. However, when inserted into a hand-piece, the nozzle may seat against a wall of the hand-piece, thereby blocking flow through one of the intake ports.